Just as global trade and international jet travel risk spreading pathogens to every country on Earth, so, the cliche runs, faster global communications and digital news media risk spreading fear to every corner of the planet. Someone sneezes in Beijing and the next moment the world is in the grip of a bird flu panic.
Last week, we saw a similar frenzy about Zika, a mosquito-borne disease that until recently did not feature in the World Health Organisation’s top 50 infectious disease threats, never mind its top 10. By any measure, Zika’s rise to the summit of the WHO fear index has been astonishing.
The disease takes its name from a remote forest in Uganda where the disease was first identified in 1947. However, following WHO director general Margaret Chan’s announcement of an international public health emergency on February 1 prompted by the spread of the virus to Central and South America and the worrying numbers of Brazilian babies born with microcephaly in the past year, it looks as if Zika will forever be associated with Brazil.
That is bad news for that country’s struggling economy, particularly in a year when it hosts the Olympics. Now, with the US Centres for Disease Control and Prevention advising pregnant women against travelling to Zika-affected countries and to abstain from sex or use condoms when having intercourse with male partners recently returned from such countries, it is also bad news for honeymooners and Caribbean islands hoping for a leap year boost to their fortunes. Altogether Zika has been recorded in 24 countries, including Barbados, Jamaica and the US Virgin Islands.
To say that nobody saw Zika coming is an understatement. Like last year’s Ebola epidemic — and the panics about swine flu and severe acute respiratory syndrome (Sars) before it — the virus blipped on almost no one’s radar. This is because, unlike other diseases transmitted by the Aedes aegypti mosquito , such as yellow fever and dengue, Zika usually results in a rash and a mild febrile illness and is not deadly. From 1947 to 2007, when the first major Zika outbreak hit Yap island in Micronesia , there were just 14 documented cases worldwide. Even when the virus sparked an epidemic in French Polynesia in late 2013 and doctors noted a marked increase in neurological and auto-immune complications, Zika caused barely a tremor.
What changed Zika’s profile and the perceptions of its danger were reports from Recife in northern Brazil last summer. While tending a woman who had just given birth to twins, a neurologist noted that one twin had a shrunken, malformed head, suggesting microcephaly, a congenital defect limiting brain development. When the physician questioned the mother more closely, she revealed that she had broken out in red spots and rashes at the beginning of her pregnancy. Soon after, he found that other mothers who had given birth to babies with microcephaly at around the same time had experienced similar rashes, suggestive of Zika infection during their pregnancies.
It is now thought that Zika probably arrived in Brazil during the World Cup in 2014. In that year Brazil recorded 147 microcephaly cases. Since health officials became aware of Zika last May, there have been in excess of 4,700 suspected microcephaly cases. Though that suggests a 30-fold increase in the condition, it has yet to be confirmed — indeed, some suspect it may have more to do with Brazil’s live birth information system (a system not readily available in less-developed countries) and overreporting (all babies with a head circumference of less than 32 centimeters are flagged as a suspected case, but many are born with small heads for other reasons)
Nevertheless, with estimates that as many as 1.5 million Brazilians and as many as four million people across the Americas may have been infected — and with criticisms of her slow response to the West African Ebola epidemic still ringing in her ears — Chan is not minded to take chances. Hence her decision to sound the highest alert possible.
Even if, as David Heymann, the chair of the WHO’s emergency Zika committee, argued last week, Zika is “not a clinically serious infection”, Chan is surely right to err on the side of caution. After all, with little or no herd immunity to the disease in the Americas, last year’s microcephaly cases could be the harbinger of worse to come. The declaration of a public health emergency should also boost R&D into much-needed vaccines and therapies; presently, the medical arsenal for Zika is empty.
Having said that, Zika is not a “fright and flight” disease like Ebola; it does not spread rapidly from person to person via bodily fluids or provoke terrifying symptoms. Nor is it thought to be particularly harmful to adults, though there have been reports of an association with Guillain-Barre syndrome, an auto-immune condition that causes paralysis.
And while health officials in several Latin American countries have advised women to avoid or delay getting pregnant, so far there is no definitive proof that it causes microcephaly. Indeed, it is hard not to resist the conclusion that, like HIV/Aids, it is the spectre of sexual transmission and the heartbreaking and highly visible defects in infants that are fuelling widespread dread of the disease, not the known risks.
Those risks, of course, are far lower if you are wealthy and can afford air-conditioning. It is surely no coincidence that it was in Recife, a city in which most of the four million inhabitants live in sprawling shanty towns interlaced with canals and stagnant pools of water, ideal for the Aedes mosquito, that the alarm was first sounded. Or that is in the favelas and communities living in the shadow of Rio’s Olympic park, where mosquitoes multiply in the puddles left by bulldozers, that Brazilian fumigation brigades are now concentrating their efforts.
As with Ebola in West Africa, engaging with local communities and persuading them to embrace simple prevention measures, such as covering exposed flesh and disposing of waterlogged tyres and plastic bottles, is likely to be the best insurance against further spread of the disease.
This is as true for Brazilians as it is for the international athletes and tourists expected in Rio this summer. And where Brazil, Colombia and other southern hemisphere countries go, so potentially goes the north. The US has already seen 30 Zika cases, including at least one due to sexual transmission. And as global warming extends the range of A aegypti, it is surely not impossible to imagine that Zika will soon be nipping at shores of Europe.
All the more reason then why, rather than recoiling from Zika and seeking to insulate ourselves from the planet’s multiplying disease threats, we should recognise that we are all in the same fight and confront our fears. Stay away from Rio this summer if you are pregnant, by all means. But for the rest of us, cancelling holidays to South America or the Caribbean because of a few hysterical headlines is unlikely to help anyone’s cause, least of all our own.
— Guardian News & Media Ltd
Mark Honigsbaum is a Wellcome Trust Research Fellow at Queen Mary University of London and author of A History of the Great Influenza Pandemics: Death, Panic and Hysteria 1830-1920
